Disclaimer: I do not own Supergirl

Author's Notes: Late prompt fill for a tumblr anon.

Sweet Sixteen

"It was supposed to be perfect! Now everything's ruined!" Alex yelled as she spun on her heel and vacated the living room to grab her surfboard propped against the back door. She ignored the expression on Kara's face as she covered her ears with the shout and she ignored the attempts of her mother at chastising her. Alex's long legs brought her to the ocean's edge in record time. Removing her shirt and jeans to reveal the mismatching sports bra and spandex shorts underneath she waded into the waves until she could mount her board and paddle out some distance.

She wasn't planning on surfing that particular moment-she hadn't been foolish enough to try without a wetsuit since she was eight-but the calm that washed over her with the lull of the ocean soothed her heart and mind temporarily. She didn't like making a big deal about her birthdays especially because they never did anything special around them, but it was been her first birthday without her father and it was her sixteenth to boot. Again, Alex couldn't care less about the 'sweet sixteen' spectacle so many at her school and around the country it seemed, made of the number. But her best friend, Vickie Donahue had wanted it to be something amazing and worked with Eliza to make the day amazing and all Alex could do was go along with the plan, wanting to make her friend happy.

Then Kara had to mess everything up. Why was she always so weird and annoying? She hadn't even wanted the girl there for the festivities but Eliza had pushed and pushed until Alex relented and agreed that it wouldn't be right to ask Kara to hide in her room the entire day. She wasn't that mean toward her new sister, but the day had been going so well and Vickie looked so ecstatic things weren't going off without a hitch that Alex just...snapped and went off at her sister for eating the first piece of cake, the piece that was supposed to be the birthday girl's. It wasn't just that one minor incident but it was the catalyst that cracked Alex and the recent cherry on the top of the other misbehaviors Kara had partook in.

Alex groaned as she paddled further out in the surf, reminding herself that Kara had no idea she was doing the wrong thing, she hadn't grown up with their customs, knew what was right in their book. Hell, she was learning something new about 'their book' every day it seemed. No, the forks go on the right side of the plate and no, it's Alex's turn to choose a movie, and you have to walk opposite of traffic so they see you and you see them. It wasn't Kara's fault Alex was a short fuse these days. The constant niggling from her mother to protect and teach and take care of Kara was grating beyond belief and caused Alex to act out further and refuse the demands when she was still on the mend from losing her father.

Her head tilted up to view the cloud covering the sun presently and realized that this was the third parental type Kara had lost. Alex growled through her teeth, double checking her ankle leash was attached before rolling off her board to dunk herself under the cold water in an attempt to chillax. Resurfacing she exhaled heavily, catching her board to rest her arms on it as the surf pushed at the pair of them. She scanned the shoreline with squinted eyes and spotted Kara watching her. Alex sighed, bowing her head for a moment before pulling herself up and waving at her sister and paddling toward shore.

When she came ashore she stuck her surfboard into the sand near Kara and sat down in the sand. Kara remained standing, a towel clutched in her hands as she continued to watch the ocean for a few silent moments. Alex glanced up at her and sighed playing with the sand at her side.

"Is everyone gone?" she asked, knowing full well she had been gone for a couple hours.

Kara nodded. "Except Vickie," she admitted, Alex smiling shyly in response. "She is a good friend," she added, finally looking at Alex. "I'm sor-"

"No," Alex cut her off, hand raised. "I'm sorry. I shouldn't have snapped at you like that. It was rude and unacceptable to take my emotions out on you. You didn't know any better," she apologized, resting her forehead against her knees.

"I understand celebrating one's birth," Kara said slowly, crouching down to sit by Alex. "But I did not know how to react, how to...engage."

Alex nodded. "I know. We should have prepared you better, helped you more. I've been...distracted with...with dad's death," she bit her lip to stave off the tears forming in her eyes. Kara looked at her and hesitating a moment, reached out to place her hand on top of one of Alex's. Alex closed her eyes as a tear slipped down her cheek and releasing a heavy breath she turned her hand over to properly grasp Kara's.

"I'm sorry," Alex whispered again. Kara shrugged then furrowed her brows. Chuckling, Alex reassured, "Yeah, you got that mannerism down." She bumped Kara's should lightly before climbing to her feet. "Let's go get some cake and icecream, huh?"

Kara grinned, the taste of the cake memorable. "Yes," she agreed reaching for Alex's surfboard as the older girl shimmied back into her jeans and pulled her shirt over her head.